Statistical analyses
The data distribution was tested for normality using the Shapiro-Wilk test and log-transformed when necessary for all the measured variables. One-way analysis of variance (ANOVA) was used to test the effects of mycorrhizal type (AM vs ECM) on nutrient absorption potential, nutrient resorption, and mass loss as well as all traits of green leaves and absorptive roots. Significant differences between means were compared using Tukey’s honest significant difference test. Correlations among processes and traits were determined by calculating Pearson’s correlation coefficients for three categories: all species and species hosting AM and ECM fungi. In order to obtain a proxy for the resource economics of green leaves, principal component analyses (PCA) were performed on a suite of leaf economics traits, including SLA, LTD, concentrations of C, N, P, and lignin in green leaves (Table S2). Based on the first axis of the PCA, we obtained the PC1 scores of each species using the ‘psych’ package in R. The standard major axis regression was then performed to evaluate the relationships between the PC1 score and nutrient-associated processes (i.e. nutrient absorption potential, nutrient resorption, and decomposition) for the three categories above using the ‘SMATR’ package in R. Results were considered statistically significant at P < 0.05. All statistical analyses were performed using R v.3.4.4 and SAS version 9.4 (SAS Institute Inc., Cary, USA).